package com.coscon.utils;


import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.StringUtils;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * @author 409390047@qq.com
 * @ClassName: RSACodeUtil
 * @Description: TODO(RSA非对称加密工具包)
 * @date 2018年10月29日 上午10:31:34
 */
public class RSACodeUtil {

    public String KEY_ALGORITHM = "RSA";
    public String SIGNATURE_ALGORITHM = "MD5withRSA";

    private String PUBLIC_KEY = "RSAPublicKey";
    private String PRIVATE_KEY = "RSAPrivateKey";

    private int MAX_ENCRYPT_BLOCK = 117;
    public int MAX_DECRYPT_BLOCK = 128;


    public byte[] decryptBase64(String key) {
        try {
            return StringUtils.isEmpty(key) ? null : Base64.decodeBase64(key);
        } catch (Exception e) {
        }
        return null;
    }

    public String encryptBase64(byte[] bytes) {
        return Base64.encodeBase64String(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     * @return
     * @throws Exception
     */
    public String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBase64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBase64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     */
    public boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBase64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBase64(sign));
    }

    public byte[] decryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
		int inputLen = data.length;
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		int offSet = 0;
		byte[] cache;
		int i = 0;
		// 对分段解密
		while (inputLen - offSet > 0) {
			if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
				cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(data, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_DECRYPT_BLOCK;
		}
		byte[] decryptedData = out.toByteArray();
		out.close();
		return decryptedData;
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public byte[] decryptByPrivateKey(String data, String key)
            throws Exception {
        return decryptByPrivateKey(decryptBase64(data), key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public byte[] decryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    public String encryptByPublicKeyString(String data, String key) throws Exception {
        return encryptBase64(encryptByPublicKey( data,  key));
    }

    /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public byte[] encryptByPublicKey(String data, String key)
            throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] mingByte = data.getBytes();
		int inputLen = mingByte.length;
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		int offSet = 0;
		byte[] cache;
		int i = 0;
		// 分段加密
		while (inputLen - offSet > 0) {
			if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
				cache = cipher.doFinal(mingByte, offSet, MAX_ENCRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(mingByte, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_ENCRYPT_BLOCK;
		}
		byte[] encryptedData = out.toByteArray();
		out.close();
		return encryptedData;

    }

    public byte[] encryptByPrivateKey(String data,String key) throws Exception {
        return encryptByPrivateKey(data.getBytes(StandardCharsets.UTF_8),key);
    }

    public String encryptByPrivateKeyString(String data,String key) throws Exception {
        return encryptBase64(encryptByPrivateKey(data,key));
    }



    /**
     * 加密<br>
     * 用私钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public byte[] encryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBase64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 取得私钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public String getPrivateKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = keyMap.get(PRIVATE_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 取得公钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public String getPublicKey(Map<String, Key> keyMap) throws Exception {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBase64(key.getEncoded());
    }

    /**
     * 初始化密钥
     *
     * @return
     * @throws Exception
     */
    public Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥
        return keyMap;
    }

    public static void main(String[] args) throws Exception {

    }
}